Ben Evans (@kittylyst) and Martijn Verburg (@karianna) have teamed up to write "The Well-Grounded Java Developer" (Covers Java 7 and Polyglot programming on the JVM). You can find their joint account on twitter (@java7developer).
Ben has been a professional developer and Open Source enthusiast since the late 90s. He has delivered world-class projects for banks, media companies and charities in that time, and currently works as an architect, lead developer and in-house Java expert at one of the world’s leading financial institutions.
Martijn Verburg is a Java/JEE and open source consultant who is passionate about software craftsmanship and the creative power of technical communities. He currently is the co-leader for the London JUG, runs two open source projects (PCGen and Ikasan EIP) and is a bartender at the Javaranch.